The role of protein metabolism in the vasculature has been investigated with regard to the pathogenesis of hypertension and stroke in genetic animal models. Based on our previous observation that incorporation of amino acids into vascular proteins in young spontaneously hypertensive rats was significantly increased, we attempted to set up a system for measuring amino acid incorporation into brain microvessels. This has been successful. Nutritional studies have demonstrated that the incidence of stroke in the stroke-prone substrain of the gentically hypertensive is related to the protein intake. This would suggest a possible correlation between dietary protein and vascular structure although this remains to be determined.